1. Technical Field
The invention relates to a gearshift unit of a so-called shift-by-wire type for motor vehicle; that is to say, a gearshift unit for electronic transmission control. The gearshift unit according to the invention is primarily intended for use in a driver's cab of a truck, but can also be advantageously used in other types of vehicle such as conventional passenger cars, so-called minivans, multi-purpose vehicles (MPVs) and sport-utility vehicles (SUVs). The gearshift unit provides a gearshift unit of the aforementioned type affording a greater safeguard against unintentional exit from the neutral position and one which enables the neutral position to be reached from other gearshift positions without wasting time.
2. Background Art
More and more vehicles are nowadays being equipped with gearshift units intended for electronic transmission control in which various gearshift positions are communicated to the gearbox by electronic signals without the existence of any mechanical clutch. In known gearshift units of this type, it is usual to fit locking units in order to prevent the gearshift lever accidentally leaving the selected gearshift position and to provide a distinct gearshift position in which the driver can feel that the gearshift has assumed its correct position. One problem with the known solutions is that a driver must perform a more complicated operation since, on the one hand, he has to release the locking mechanism, and on the other must find the neutral position in those situations where the neutral position needs to be rapidly engaged. An example of a situation in which the neutral position must be rapidly engaged is where a driver has to correct a skid. Where a manual gearbox is used, the neutral position can be easily obtained by depressing the clutch pedal. There is no corresponding facility in a gearshift unit with electronic transmission control. It is usual, however, to prevent accidental engagement of the reverse gear in that, in the absence of any pressure on a button or its depression by the driver, the gearshift is locked between the neutral and reverse positions. This means, however, that the neutral position cannot be reached directly without additional movements on the part of the driver when the reverse gear is engaged. The time wasted as a result of this lock makes rapid maneuvers more difficult for the driver, which makes the vehicle less comfortable to drive in critical situations.